Sunday, April 30, 2017

To the Land of Volcanic Enchantment (LoVE)

New Mexico’s official nickname is “Land of Enchantment”because of its rich scenery, long record of human history (for the US), and the many diverse cultures. Other nicknames popular enough to appear on license plates reference Cactus, Spanish, Sunshine, Delight Makers, Opportunity, Heart’s Desire, and most recently Chile Capital of the World. But oddly, none mention volcanoes.

This is so wrong! Much of the state is covered in volcanic rock, from basalt flows to massive beds of welded tuff. The most recent activity was just 45,000 years ago, and it isn't over yet. For example, only 20 km below the town of Socorro, an area of intense microearthquakes, a huge magma body lies waiting. The state really is a volcanic wonderland  which is why I'm going there later this week.

New Mexico is a geotripper’s paradise in general. Landforms are diverse. Rocks range from ancient crust (1.5+ billion years old) to the recent volcanics. Due to a dry climate, vegetation is sparse and plants don't obscure the landscape. Thus we often can make sense of what we see. However, my specific destination is an exception. The Jemez Lineament is one of the most prominent volcanic features in the state, and yet it may be the most mysterious. In 1984, volcanologists Smith and Luedke called it “the most spectacular phenomenon of its kind in the US … and not easily understood.” Thirty years later, their words still apply.
Volcanic fields of the Jemez Lineament, with Socorro Magma Body added (source unknown).
The Jemez Lineament is an obvious 800-km line of volcanic fields that spans northern New Mexico—from the Raton-Clayton volcanic field in the northeast corner, to the Zuni-Bandera field near Grants, and on into Arizona. It crosses multiple major tectonic provinces: the Great Plains, southern Rocky Mountains, Basin and Range Province, and Colorado Plateau. Features include cinder cones, lava flows, calderas, maars, shield volcanoes, composite cones, volcanic necks and more. The rocks are relatively young, erupted in the last nine million years. Most are basaltic (the one major exception is the Valles Caldera).
Capulin Volcano lies near the northeast end of the Jemez Lineament (L. Crumpler; source).
Aerial view of Valles Caldera—so large that it’s hard to grasp from the ground (L. Crumpler; source).
The Zuni-Bandera field near Grants includes the youngest eruptions in the state, such as McCarty’s flow (view from 20,000 ft; L. Crumpler; source).

Early on, some geologists assumed the Jemez Lineament was a hotspot chain—a line of volcanic activity resulting from the continent moving over a hotspot in the mantle. It parallels a line of volcanism to the north in Idaho and Yellowstone, considered by many to be a hotspot trace. However, the Jemez Lineament doesn't fit the hotspot model because there’s no time progression. Younger and older features are lined up in no particular order. [Even though the hotspot hypothesis has been rejected, Wikipedia refers to the Jemez Lineament as the “Raton hotspot trail.”]

Currently, the most popular hypothesis invokes events from the deep past, when North America was a smaller continent. From 1.8 to 1.6 billion years ago (Paleoproterozoic), several large crustal fragments and/or volcanic arcs drifted north and collided with the southern margin of proto-North America, enlarging it by 1500 km in just 200 million years.
The American Southwest in the Paleoproterozoic Era (source, modified).
The suture between the young continent (aka Wyoming craton, green in map above) and the Mojave and Yavapai terranes is known as the Cheyenne Belt. I live just south of it, and it's nicely exposed in the Medicine Bow Mountains west of town. Very different rocks occur on either side of a narrow zone of contorted rocks mangled during collision; this is the ancient suture. In contrast, the boundary between the Yavapai (pink) and Mazatzal (blue) terranes is “diffuse and elusive” (Magnani et al. 2005). It's considered a broad transition zone (purple in map) where rocks from both terranes are exposed. Even the boundaries of the transition zone are hard to pinpoint; the sharp lines on maps are misleading.

Adding the Jemez Lineament to the map of Paleoproterozoic terranes reveals a seductive pattern (below). The volcanic fields of the Lineament (black blobs) line up with the Yavapai-Mazatzal transition zone! It's tempting to think that crustal collision 1.6 billion years ago is still shaping the landscape. Perhaps the old suture has provided pathways through the crust for magma to reach the surface.

A pre-existing structure shows up in many explanations of the Jemez Lineament:
“magma leaked through the broken crust” (interpretive sign)
“… a zone of apparent crustal weakness geologists call the Jemez lineament” (Price 2010)
“Although there’s no simple answer to this question, clearly the answer must involve some major structural feature deep within the earth’s crust” (Muehlberger et al. 2003).
“Some geologists consider the Jemez lineament to be a reactivated Precambrian suture or boundary; … some structural or tectonic features of the Jemez lineament must penetrate through the crust into the mantle, because the most significant volumes of [Quaternary] volcanic rocks in New Mexico are erupted along this zone (Goff 2009).
“It may coincide with a boundary between Proterozoic lithospheric age provinces (a suture zone), which in effect exerts control on the present-day disassembly of the lithosphere” (Baldridge 2004).
Baldridge’s suggestion that the crust is coming apart (“disassembly”), perhaps along an ancient suture, is not just some wacko idea. Much of New Mexico has been undergoing extension for the last 30 million years. The most obvious evidence is the Rio Grand Rift, which has widened to almost 100 km in places (map below; source). Maybe thirty million years of stretching has loosened the Yavapai-Mazatzal suture enough to allow magma to ascend to form the Jemez Lineament.
In 2005, Magnani and colleagues reported that near Las Vegas, New Mexico, the ancient Yavapai-Mazatzal suture does indeed lie beneath the Jemez Lineament (reflection seismology profile below). They also noted that a mantle anomaly (hotter) had been documented in the same area. In other words, there’s now suggestive evidence for both a magma source and a conduit beneath the Jemez Lineament. Perhaps we’re starting to piece together the story of this “most spectacular phenomenon.”
The magic of reflection seismology requires humongous amounts of computer processing time (source (free)).

If you go …

Though the state nick-namers have ignored New Mexico volcanism, other agencies give it the attention it deserves. The Bureau of Geology and Mineral Resources, and the University of New Mexico Press have published excellent affordable books for those who want to see and learn about the state’s volcanic features and geology in general (flagged ** in Sources below). In addition, several very cool interactive websites can help you plan your trip: Volcanoes of New Mexico and Virtual Geologic Tour of New Mexico.

Sources (in addition to links in post)

** less technical but full of information, with photos, figures, maps and more

Baldridge, WS. 2004. Pliocene-Quaternary volcanism in New Mexico and a model for genesis of magmas in continental extension, in Mack, GH, and Giles, KA, eds. The geology of New Mexico, a geologic history. New Mexico Geological Society Special Publication 11.

Dunbar, NW. 2005. Quaternary volcanism in New Mexico, in Lucas, SG, MOrgan GS, and Zeigler, KE, eds. New Mexico’s ice ages. NM Institute of Mining and Technology Bulletin 28:95-106.

** Goff, F. 2009. Valles Caldera, a geologic history. University of New Mexico Press.

Magnani, MB, et al. 2005. Seismic Investigation of the Yavapai-Mazatzal Transition Zone and the Jemez Lineament in Northeastern New Mexico, in Karlstrom, KE, and Keller, GR, eds. The Rocky Mountain Region—an evolving lithosphere: tectonics, geochemistry, and geophysics. (2005), AGU, Washington, D. C.Geophys. Monogr. Ser. 154: 227-238. Free.

** Muehlberger, WR, Muehlberger, SJ, and Price, LG. 2005. High Plains of northeastern New Mexico, a guide to geology and culture. NM Bureau of Geology and Mineral Resources.

** Price, LG., ed. 2010. The geology of northern New Mexico’s parks, monuments, and public lands. NM Bureau of Geology and Mineral Resources.

Smith, RI, and Luedke, RG. 1984. Potentially active volcanic lineaments and loci in western conterminous United States, in Explosive volcanism: inception, evolution, and hazards. Washington DC, National Academy Press, Washington: 47-66.

Friday, April 21, 2017

Pseudoflowers—Trick or Treat?

A flower-less rockcress.

Every spring some of our rockcresses forego flowering, and instead grow terminal clusters of fragrant yellow leaves dotted with sugary goo. But why? Generally plants produce color, fragrance and nectar to lure pollinators, which carry male gametes (pollen) off to where female gametes (ovules) await fertilization. But the yellow-leaved rockcresses have no flowers, no pollen, no ovules. And yet these plants are all about sex—fungal sex that is.

Rockcresses (Boechera spp.; formerly Arabis) are members of the mustard family. Most are perennials, with a few biennials. They usually produce white to pale pink or purple flowers, but the yellow-leaved versions are common enough to frequently confuse wild-flower enthusiasts.
“Almost every spring, someone brings me a picture or a plant of a strange little flower they’ve never seen before, and can’t key out or even begin to guess the family for.” Irene Shonle
“Strange little flower” (source).
Normal rockcress, and infected rockcress with pseudoflowers (Cano et al. 2013).

The yellowed rockcresses are infected with Puccinia monoica—mustard flower rust. Rust fungi are obligate plant pathogens, and include some of the most destructive agricultural pests (e.g. wheatstem rust, coffee rust). Some have extremely complex life cycles, involving five spore types and multiple host species in a single life cycle! (details here)

The life of the mustard flower rust is simpler, requiring three spore types and one or two hosts (full story here). If a wind-blown basidospore (which has a single haploid nucleus) is lucky enough to land on a suitable host plant, it germinates. Hyphae grow into the stem, tapping into the plant’s nutrient supply. But living happily ever after on a rockcress is not part of the rust's plan. Sex is its goal. Mustard flower rust is heterothallic, meaning opposite mating types are produced by separate “individuals” (rust infections) on separate rockcress plants. Opposite mating types need to get together somehow.

Puccinia monoica solves this problem by creating pseudoflowers. Like real flowers, they attract pollinators (mostly insects) by way of fragrance and the promise of sweet reward. How impressive that a simple little fungus has evolved to to grow such features! … except that’s not what happens, at least not directly. The real story is even more amazing. The plant grows these novel features … under the direction of the rust!
In addition to siphoning off nutrients, the rust reprograms the host plant, somehow changing which genes are expressed when. As a result, the infected rockcress never makes the transition from vegetative growth to flowering. Instead it elongates, grows extra leaves, and produces yellow pigment, fragrant compounds, sugary liquid, and wax. The resulting structure looks, smells and tastes enough like a flower that foraging insects show up, partake of a bit of sugar, and hopefully carry off the spore-like spermatia to receptive hypha on other rockcresses.
Bumps are spermagonia, which contain spores waiting to be dispersed and super-sweet liquid.
Pseudoflowers may mimic other wildflowers, like this nearby sagebrush buttercup (speculation for now).
With today’s molecular analysis techniques and model organisms (Arabidopsis thaliana, the thale cress, is a close relative of rockcresses), it’s possible to delve deeply into pseudoflower biology. In 2013, Liliana Cano and her colleagues looked at developmental changes in rockcresses infected with mustard flower rust. They found that for at least 31 genes, activity was significantly altered (enhanced or reduced), affecting leaf, stem and flower development; metabolism and transport of sugars and lipids; synthesis of volatiles (fragrant compounds); and wax production.

These changes can be interpreted as beneficial to the mustard flower rust. For example, consider wax production. Cano and colleagues suggest that the waxy leaves induced by rust infection serve to reduce water stress. Water-stressed plants often have shorter stems and fewer leaves—not what the rust needs. Perhaps the waxy leaves of infected plants allow taller leafier growth.
Gravelly soil drains rapidly, making for dry habitat. Looks like waxy leaves weren't enough to compensate.

Whatever the mechanisms, by enabling fungal sex, infection clearly benefits the rust. And the rockcress clearly suffers—no flowers, no sex. But what about pollinators? Are they beneficiaries or unsuspecting dupes? Some botanists consider pseudoflowers to be tricksters, luring insects into service with little reward. However in a 1998 paper, Robert Raguso and Bitty Roy pointed out that the super sweet liquid of rockcress pseudoflowers is popular with many kinds of insects, including bees, ants, butterflies and flies. And given how many sugar-oozing spermagonia there are on each yellow leaf, infected rockcresses may actually produce more yummy calories than uninfected plants. If so, then for pollinators, pseudoflowers are not a trick but a treat.
Foraging ant (in a hurry).

Puccinia monoica on Boechera sp. is the latest addition to my iNaturalist project, Plants of the Southern Laramie Mountains (two observations—one for the rust, one for the plant). To identify the rockcress to species, I have to wait until uninfected individuals are in fruit.
I found infected rockcresses scattered through this sagebrush grassland.
It’s still early spring at Blair (8000 feet elevation)—not much flower action.


Thanks to Elio Schaechter of Small Things Considered who recently blogged about Boechera pseudoflowers, which I’ve long ignored.

Caro, LM, et al. 2013. Major transcriptome reprogramming underlies floral mimicry induced by the rust fungus Puccinia monoica in Boechera stricta. PLoS ONE 8(9): e75293. (free).

Raguso, RA, and Roy, BA. 1998. ‘Floral’ scent production by Puccinia rust fungi that mimic flowers. Molecular Ecology (1998) 7, 1127-1136.

Wednesday, April 12, 2017

Wyoming Native Plant Society helps liberate Plant Names for Creative Re-use

What's your pleasure?

Let’s say you’re writing an article about a plant, or your local flora, or a pioneering botanist. Now … close your eyes and imagine you’re in a huge library dedicated exclusively to biodiversity, with 200,000+ holdings (many rare) scattered across the globe. Next, imagine giving the name of your plant or botanist to a “librarian” who then piles all relevant books, articles, field notes, correspondence, etc., on your desk almost instantaneously! In fact, this library is not imaginary. It’s quite real, though in a virtual kind of way. It’s the Biodiversity Heritage Libraryheadquartered at the Smithsonian Institution in Washington DC, but easily accessible from your office, home, or favorite coffee house.

I discovered the BHL in 2014, while putting together a post about the history of the lanceleaf cottonwood (Populus acuminata). BHL soon became my go-to site for information about botanical exploration of the American West. What I like most is the quick easy access to lots of useful information. Documents that were difficult to access or even unavailable only a few years ago are now just a search and a click away.
Per Axel Rydberg’s Populus acuminata. From American Black Cottonwoods, 1893; BHL.
Edwin James’s Jamesia. From Curtis’s Botanical Magazine, 1875; BHL.
Fossilized palm frond (Powell palmetto perhaps?) collected near Rock Springs, Wyoming. From JS Newberry’s The later extinct floras of North America, 1898; BHL.

The BHL is a consortium of natural history and botanical libraries that are digitizing legacy biodiversity literature, making it easily accessible as part of a global “biodiversity commons.” Much of this literature has been available only in select libraries, mainly in the developed world, making limited access a major obstacle—for example in research, conservation and education. Providing it online free-of-charge is a radical and exciting change. “Free global access to digital literature repatriates information about the earth’s species to all parts of the world.”

Put another way, BHL is making biodiversity literature “freely accessible to a global audience … thereby liberating taxonomic names and bibliographic data associated with the content for creative re-use.” Among the plant names most recently liberated were those in our very own Castilleja, the newsletter of the Wyoming Native Plant Society.
In October 1994, the Wyoming Native Plant Society newsletter was given a name: Castilleja.

It all started last October when the BHL blog featured a post titled A Local Focus: The Native Plant Societies of the US. When I read that native plant society newsletters were being added to the collection, I contacted Project Investigator Susan Fraser at The New York Botanical Garden, asking if Castilleja were part of the plan. Indeed it was. “We would be thrilled to include Castilleja in the project,” she replied.

Incorporating native plant society newsletters into the BHL is part of Expanding Access to Biodiversity Literature—a two-year project designed to “preserve and provide access to small natural history and botanical collections and publications.” It’s conducted by the New York Botanical Garden in partnership with Harvard University, the Missouri Botanical Garden, and the Smithsonian Institution Libraries.
“We are grateful to the native plant societies who have generously shared their local expertise by making their newsletters available to researchers through BHL. In addition to the biodiversity information they contain, these publications are a wonderful snapshot of the small, dedicated groups of people working all over the U.S. to document and preserve our native plants.” –Patrick Randall, Community Manager, Expanding Access to Biodiversity Literature; Ernst Mayr Library, Harvard University

Before Castilleja issues could be processed, a permissions form had to be signed (the society President took care of this). Fortunately, PDFs were available for all issues; these were transmitted en masse to BHL. Then the techies worked their magic. Now, whenever someone searches BHL for Boechera pusilla or Yermo xanthocephalus, for example, relevant issues of Castilleja appear on the results list. We’ve hit the big time!

The image below shows one result from a BHL search for “yermo xanthocephalus”—the desert yellowhead, endemic to Wyoming. As I scrolled through Castilleja Volume 17 Number 4 (1998), scientific names on each page appeared in the box on the lower left. Note that contents can be printed or downloaded (either the entire work or selected pages). I’ve used the latter option many times. Usually the pages arrive well within the hour, whether from the newsletter of a neighboring native plant society, or from a rare old book in a library thousands of miles away.

How did BHL manage to find yermo among the 51,749,439 pages held in the collection? It was magic!!! No, not really … sorry. But it’s just as cool as magic. As texts are processed, scientific names are extracted from each page using Global Names Recognition and Discovery (GNRD), a taxonomic name recognition algorithm. GNRD provides an open and global-names-based infrastructure to index, organize and manage biodiversity data. Like BHL, GNRD aims for easy public access, with the goal of spurring widespread and innovative use of biodiversity data. A noble goal indeed!

So if you’re in need of biodiversity literature, especially if it’s old or rare or otherwise difficult to access, pay a visit to the BHL. Adventure and discovery start here. And if you’re looking for a good time, browse the always-interesting BHL blog (warning: you'd better have plenty of time on your hands).
Above, Coffea arabica was the first coffee species to be cultivated, and still accounts for most of world's coffee production (from Köhler's Medizinal-Pflanzen; see The Berry that Changed the World). Below, Miss C.H. Lippincott Flower Seeds catalog cover (1900), from Leading Ladies in the World of Seeds (you can view over 11,000 seed and nursery catalogs in the BHL collection!).

Friday, April 7, 2017

Following a Tree, from Fronds to Rebar

April 7 has arrived, and being a tree-follower, I’m posting the latest news of my tree at the monthly gathering kindly hosted by The Squirrelbasket. If you like trees and would like to join us, check out the links above (it’s interesting and fun, with no obligation).

This year I’m following an extinct tree—Sabalites powellii, a palm that grew in southwest Wyoming 50 million years ago. I discovered it in December in our Geology Museum, and in May I will visit its ancient habitat. In the meantime, tree-following consists of learning about Sabalites and its world. This month, I decided to look into its wood. The Green River Formation—the rock layers where fossilized fronds have been found—also contains fossilized palm wood. It’s common, beautiful, and popular with collectors.
Fossilized palm wood is the state rock of Texas (source).
However, my search for “Sabalites wood” was futile, both in Google and the scientific literature. That’s because fossil palm wood is called Palmoxylon. Is this weird? Are paleobotanists exceptionally obsessed with publishing new names?
Sabalites powellii, a fossil palm frond “species” from southwest Wyoming.
Palmoxylon includes 200+ “species” of fossil palm wood (source).
Plant fossil names proliferate because paleobotanists are faced with an unfortunate situation. Most fossilized plants are actually fossilized plant parts—leaves, branches, flowers, etc., that fell off some plant. Generally there’s no way to know if different parts came from the same species, so they’re given different names.

Palm wood usually is easy to recognize. Cutting a petrified palm trunk cross-wise reveals a characteristic pattern of scattered dots—the vascular bundles that conduct water and nutrients up and down trees.
Cross-section through petrified Palmoxylon log (click on image to view dots; source).
Length-wise view of Palmoxylon (source). Xylon means “one having (such) wood—in generic names” (Merriam-Webster) … in this case, having palm wood.
In most trees (dicots), vascular bundles are arranged near the perimeter, but in monocots, they're scattered through the stem (diagram below). Monocots include orchids, grasses, lilies and more. Most are herbaceous, but a few produce wood and grow large, e.g. yuccas, bamboos and palms.
Cross-sections through dicot and monocot stems (source, modified).

Wait a minute!!! As botany students we're taught that monocots don’t make wood. Wood is produced by secondary growth in the vascular cambium (below), and monocots have no vascular cambium. Yet palms are monocots and obviously woody … ??
In dicots, wood develops from secondary growth via the vascular cambium (source, modified).
Large monocots are said to produce strong trunks through abnormal secondary growth. I think we call it “abnormal” because it’s disorderly and hard to categorize … and poorly understood. Webpage after webpage explains that palms thicken their trunks through diffuse secondary growth, in which parenchyma cells divide and enlarge. And yet a recent study revealed that at least some palms have a vascular-cambium-like meristem! (Botánico & Angyalossy 2013; article here):
“… we analysed palm stems of four species, with the aim to understand the possible presence of such secondary growth. We found that a meristematic band occurs between the cortex and the central cylinder and gives rise to new vascular bundles and parenchyma internally, producing parenchyma and fibres externally. … In fact, a meristematic band is present and may be more common than currently believed, but uneasy to detect in certain palms for being restricted to specific regions of their stems.”

Palms’ tough rigid tissue may not be “true wood,” but it’s called wood and functions as wood. Some kinds are used in construction, including that of the coconut palm. Wood from the outer part of the trunk, where the vascular bundles are dense, is harder even than oak and Douglas fir (source).

In fact, sometimes palm wood is better than true wood. It's more flexible—palms can bend 40º without breaking! The tough fibrous vascular bundles scattered through the trunk serve as plant rebar—like the steel rods that give strength and flexibility to reinforced concrete.
Flexibility is a great adaptation in hurricane-prone environments. Courtesy US Navy.
When a tropical cyclone tore through this rainforest, the palms were left standing (source).

We'll stop here. Once again, tree-following has taken me on a winding journey, this time to fossil palm wood, woody monocots, meristems, vascular bundles and finally rebar. We’re lucky there’s so much of interest in this world!

Thanks to Mike of CSMS Geology Post, for continued paleontological guidance.